1. Field
One or more embodiments of the present invention relate to a secondary battery, and more particularly, to a structure of a secondary battery.
2. Description of the Related Art
In general, rechargeable secondary batteries, have been widely used in high-tech electronic devices such as cellular phones, notebook computers, and camcorders. In particular, lithium secondary batteries have a working voltage that is three times greater than those of nickel-cadmium (Ni—Cd) batteries and nickel-hydrogen (Ni—MH) batteries and are commonly used as power sources of electronic devices. Lithium secondary batteries also have a relatively great energy density per unit weight. Thus, much research into lithium secondary batteries has been performed.
Lithium secondary batteries are classified into liquid electrolyte batteries and polymer electrolyte batteries according to types of electrolytes. In general, lithium secondary batteries that contain a liquid electrolyte are called lithium ion batteries, and lithium secondary batteries that contain a polymer electrolyte are called lithium polymer batteries.
Lithium ion batteries use carbon in a negative electrode, a lithium oxide in a positive electrode, and an organic solvent electrolyte in an electrolytic solution. In lithium ion batteries, lithium ions reciprocate between a positive electrode and a negative electrode to generate electricity. Since lithium has a low charge and discharge efficiency, lithium ion batteries can be rapidly charged by intercalating lithium ions into a carbon layer having a high reaction rate. Lithium ion batteries may be manufactured in various shapes, for example, in a cylindrical shape or a square pillar shape.
In lithium ion batteries, a case may accommodate an electrode assembly and an electrolytic solution. If the electrolyte solution leaks during operation of the lithium ion batteries or during charging and discharging processes, a short circuit may occur or electronic devices around the lithium ion batteries may be contaminated.